1. Field of the Invention
The present invention relates to a mechanism for converting rotary motion into linear motion that mutually converts between rotary motion and linear motion, and relates to a lifting device that converts rotary motion of a rotary drive source such as a motor to linear motion for linearly driving an object.
2. Description of the Related Art
For example, in Japanese Patent Application Laid-open 2007-120658 (FIG. 2 and FIG. 11), there is proposed a mechanism for converting rotary motion into linear motion including, a rod having a threaded portion constituting its outer surface, a holder member disposed on the outer surface of the rod so as to be rotatable and movable in an axial direction relative to the rod, and a plurality of rollers that is supported rotatably on the holder member having a plurality of annular grooves that is in mesh with a threaded portion on an outer surface of the roller, and converts the rotation of the roller (holder member) into linear motion of the rod by the mesh.
In such a mechanism for converting rotary motion into linear motion, it is required, for example, to improve positioning accuracy in linear motion converted from rotary motion.
Accordingly, it is an objective of the present invention to provide a mechanism for converting rotary motion into linear motion that mutually converts between rotary motion and linear motion with high positioning accuracy, and to provide a lifting device that is equipped with the mechanism for converting rotary motion into linear motion.